I set my wall clock with the current timing on my phone about a couple of months ago and today I saw it was lagging behind by 7 mins
In: Physics
Most wall clocks are standalone devices probably relying on an electronic crystal to keep time. Although they are fairly accurate, left alone it will eventually drift because the (low cost) circuit isn’t comparable to much more expensive atomic clocks used as a time reference. Some clocks lose time and some will gain time. It just so happens that yours loses time.
Your phone also relies on an internal crystal/clock to keep time but if it is connected to the internet, it regularly corrects itself to the local time standards which are usually kept by those very expensive atomic clocks. Therefore the mobile phone clock doesn’t drift over time.
Both digital and analog clocks measure time by looking at how a specific object swings back and forth and counting the number of swings. An analog clock have a pendulum or a weighted wheel while a digital clock have a specific crystal like a tuning fork. The problem is that this object may not be shaped perfectly so it might not have the exact right amount of swings in a second. With a pendulum you can often adjust its length to solve this. The other problem is that things like temperature, pressure, humidity, etc. can alter how fast it swings. And this might require constant adjustments which itself might not be completely accurate.
Your phone have a built inn service which checks the exact time with a networks of accurate clocks around the world. This is done either by the cell phone network, GPS or the Internet. The phone is then not only able to set the time correctly from time to time but also adjust the clock by changing how many cycles it counts to for every second. You can get wall clocks with similar features. But these are often more expensive and usually say so in rather prominent text on the front.
The mechanical aspect, it takes time to turn those gears. Very little time, at first its not noticable but ovwr timw those small increments add up to minutes
Digital clocks, analog clocks, and basically every other type of clock that isn’t an atomic clock will eventually fall out of sync with what we consider to be “accurate time.”
For example, your digital clock counts a second as *barely* longer than an actual second. It’s probably taking something like 60.00001 seconds for your clock to count out 60 “real” seconds. Over a day, or a week, or a month or two, it probably won’t make a big difference, but it will eventually.
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